Gas problem
Climate Clubs: Overcoming Free-Riding in International Climate Policy
William Nordhaus
American Economic Review, April 2015, Pages 1339-1370
Abstract:
Notwithstanding great progress in scientific and economic understanding of climate change, it has proven difficult to forge international agreements because of free-riding, as seen in the defunct Kyoto Protocol. This study examines the club as a model for international climate policy. Based on economic theory and empirical modeling, it finds that without sanctions against non-participants there are no stable coalitions other than those with minimal abatement. By contrast, a regime with small trade penalties on non-participants, a Climate Club, can induce a large stable coalition with high levels of abatement.
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Environmental tipping points significantly affect the cost−benefit assessment of climate policies
Yongyang Cai et al.
Proceedings of the National Academy of Sciences, 14 April 2015, Pages 4606–4611
Abstract:
Most current cost−benefit analyses of climate change policies suggest an optimal global climate policy that is significantly less stringent than the level required to meet the internationally agreed 2 °C target. This is partly because the sum of estimated economic damage of climate change across various sectors, such as energy use and changes in agricultural production, results in only a small economic loss or even a small economic gain in the gross world product under predicted levels of climate change. However, those cost−benefit analyses rarely take account of environmental tipping points leading to abrupt and irreversible impacts on market and nonmarket goods and services, including those provided by the climate and by ecosystems. Here we show that including environmental tipping point impacts in a stochastic dynamic integrated assessment model profoundly alters cost−benefit assessment of global climate policy. The risk of a tipping point, even if it only has nonmarket impacts, could substantially increase the present optimal carbon tax. For example, a risk of only 5% loss in nonmarket goods that occurs with a 5% annual probability at 4 °C increase of the global surface temperature causes an immediate two-thirds increase in optimal carbon tax. If the tipping point also has a 5% impact on market goods, the optimal carbon tax increases by more than a factor of 3. Hence existing cost−benefit assessments of global climate policy may be significantly underestimating the needs for controlling climate change.
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Optimal Carbon Abatement in a Stochastic Equilibrium Model with Climate Change
Christoph Hambel, Holger Kraft & Eduardo Schwartz
NBER Working Paper, March 2015
Abstract:
This paper studies a dynamic stochastic general equilibrium model involving climate change. Our model allows for damages on economic growth resulting from global warming. In the calibration, we capture effects from climate change and feedback effects on the temperature dynamics. We solve for the optimal state-dependent abatement policy. In our simulations, the costs of this policy measured in terms of lost GDP growth are moderate. On the other hand, postponing abatement action could reduce the probability that the climate can be stabilized. For instance, waiting for 10 years reduces this probability from 60% to 30%. Waiting for another 10 years leads to a probability that is less than 10%. Finally, doing nothing opens the risk that temperatures might explode and economic growth decreases significantly.
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Emissions Abatement: Untangling the Impacts of the EU ETS and the Economic Crisis
Germà Bel & Stephan Joseph
Energy Economics, forthcoming
Abstract:
In this study we use historical emission data from installations under the European Union Emissions Trading System (EU ETS) to evaluate the impact of this policy on greenhouse gas emissions during the first two trading phases (2005–2012). As such the analysis seeks to disentangle two causes of emission abatement: that attributable to the EU ETS and that attributable to the economic crisis that hit the EU in 2008/09. To do so, we use a dynamic panel data approach. Our results suggest that, by far, the biggest share of abatement was attributable to the effects of the economic crisis. This finding has serious implications for future policy adjustments affecting core elements of the EU ETS, including the distribution of EU emission allowances.
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The Effect of Global Warming on Severe Thunderstorms in the United States
Jacob Seeley & David Romps
Journal of Climate, March 2015, Pages 2443–2458
Abstract:
How will warming temperatures influence thunderstorm severity? This question can be explored by using climate models to diagnose changes in large-scale convective instability (CAPE) and wind shear, conditions that are known to be conducive to the formation of severe thunderstorms. First, an ensemble of climate models from phase 5 of the Coupled Model Intercomparison Project (CMIP5) is evaluated on its ability to reproduce a radiosonde climatology of such storm-favorable conditions in the current climate’s spring and summer seasons, focusing on the contiguous United States (CONUS). Of the 11 climate models evaluated, a high-performing subset of four (GFDL CM3, GFDL-ESM2M, MRI-CGCM3, and NorESM1-M) is identified. Second, the twenty-first-century changes in the frequency of environments favorable to severe thunderstorms are calculated in these high-performing models as they are forced by the RCP4.5 and RCP8.5 emissions pathways. For the RCP8.5 scenario, the models predict consistent CONUS-mean fractional springtime increases in the range of 50%–180% by the end of the twenty-first century; for the summer, three of the four models predict increases in the range of 40%–120% and one model predicts a small decrease. This disagreement between the models is traced to divergent projections for future CAPE and boundary layer humidity in the Great Plains. This paper also explores the sensitivity of the results to the relative weight given to wind shear in determining how “favorable” a large-scale environment is for the development of severe thunderstorms, and it is found that this weighting is not the dominant source of uncertainty in projections of future thunderstorm severity.
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James Neumann et al.
Climatic Change, March 2015, Pages 337-349
Abstract:
Recent literature, the US Global Change Research Program’s National Climate Assessment, and recent events, such as Hurricane Sandy, highlight the need to take better account of both storm surge and sea-level rise (SLR) in assessing coastal risks of climate change. This study combines three models — a tropical cyclone simulation model; a storm surge model; and a model for economic impact and adaptation — to estimate the joint effects of storm surge and SLR for the US coast through 2100. The model is tested using multiple SLR scenarios, including those incorporating estimates of dynamic ice-sheet melting, two global greenhouse gas (GHG) mitigation policy scenarios, and multiple general circulation model climate sensitivities. The results illustrate that a large area of coastal land and property is at risk of damage from storm surge today; that land area and economic value at risk expands over time as seas rise and as storms become more intense; that adaptation is a cost-effective response to this risk, but residual impacts remain after adaptation measures are in place; that incorporating site-specific episodic storm surge increases national damage estimates by a factor of two relative to SLR-only estimates, with greater impact on the East and Gulf coasts; and that mitigation of GHGs contributes to significant lessening of damages. For a mid-range climate-sensitivity scenario that incorporates dynamic ice sheet melting, the approach yields national estimates of the impacts of storm surge and SLR of $990 billion through 2100 (net of adaptation, cumulative undiscounted 2005$); GHG mitigation policy reduces the impacts of the mid-range climate-sensitivity estimates by $84 to $100 billion.
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Volume loss from Antarctic ice shelves is accelerating
Fernando Paolo, Helen Fricker & Laurie Padman
Science, 17 April 2015, Pages 327-331
Abstract:
The floating ice shelves surrounding the Antarctic Ice Sheet restrain the grounded ice-sheet flow. Thinning of an ice shelf reduces this effect, leading to an increase in ice discharge to the ocean. Using eighteen years of continuous satellite radar altimeter observations we have computed decadal-scale changes in ice-shelf thickness around the Antarctic continent. Overall, average ice-shelf volume change accelerated from negligible loss at 25 ± 64 km3 per year for 1994-2003 to rapid loss of 310 ± 74 km3 per year for 2003-2012. West Antarctic losses increased by 70% in the last decade, and earlier volume gain by East Antarctic ice shelves ceased. In the Amundsen and Bellingshausen regions, some ice shelves have lost up to 18% of their thickness in less than two decades.
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Efficient use of land to meet sustainable energy needs
Rebecca Hernandez, Madison Hoffacker & Christopher Field
Nature Climate Change, April 2015, Pages 353–358
Abstract:
The deployment of renewable energy systems, such as solar energy, to achieve universal access to electricity, heat and transportation, and to mitigate climate change is arguably the most exigent challenge facing humans today. However, the goal of rapidly developing solar energy systems is complicated by land and environmental constraints, increasing uncertainty about the future of the global energy landscape. Here, we test the hypothesis that land, energy and environmental compatibility can be achieved with small- and utility-scale solar energy within existing developed areas in the state of California (USA), a global solar energy hotspot. We found that the quantity of accessible energy potentially produced from photovoltaic (PV) and concentrating solar power (CSP) within the built environment (‘compatible’) exceeds current statewide demand. We identify additional sites beyond the built environment (‘potentially compatible’) that further augment this potential. Areas for small- and utility-scale solar energy development within the built environment comprise 11,000–15,000 and 6,000 TWh yr−1 of PV and CSP generation-based potential, respectively, and could meet the state of California’s energy consumptive demand three to five times over. Solar energy within the built environment may be an overlooked opportunity for meeting sustainable energy needs in places with land and environmental constraints.
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Gregory McCabe, Julio Betancourt & Song Feng
International Journal of Climatology, forthcoming
Abstract:
The timing of last spring frost dates (LSFDs), first fall frost dates (FFFDs), and frost-free period lengths (FFPLs) constrains freeze–thaw processes in hydrology, paces the annual life cycles of plants and animals, affects human food production, and influences land–atmosphere interactions, including the water and carbon cycles. Daily minimum temperature data for the conterminous United States (CONUS) from the Global Historical Climatology Network for the 1920–2012 period are used to determine LSFDs, FFFDs, and FFPLs. Analyses of trends and variability in these growing season components indicate a trend towards earlier LSFDs, later FFFDs, and longer FFPLs for most locations in the CONUS. A general change to earlier LSFDs appears to have occurred after about 1983, whereas a change to later FFFDs is most noticeable after about 1993. Comparisons of time series of LSFDs and FFFDs with well-known climate indices indicate only weak correlations for most sites.
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Elizabeth Marshall et al.
American Journal of Agricultural Economics, March 2015, Pages 568-588
Abstract:
General circulation models predict significant and accelerating changes in local patterns of precipitation and temperature during the twenty-first century. Agriculture's vulnerability to climate change will depend on both the biophysical impacts of climate change on crop yields and on the agricultural system's ability to adapt to changing production conditions. Shifts in the extent and distribution of irrigated and dryland production are a potentially important adaptation response. Farmer flexibility to adapt may be limited, however, by changes in the availability of irrigation water under future climate conditions. This study uses a suite of models to explore the biophysical and economic impacts of climate change on U.S. fieldcrop production under several potential future climate projections, and to explore the potential limits and opportunities for adaptation arising from shifting regional water balances. The study findings suggest that, while irrigation shortages attributable to climate change have varying effects on cropland use, the aggregate impacts on national production are small relative to the direct biophysical impacts of climate change on yield.
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Moving Matters: The Effect of Location on Crop Production
Jason Beddow & Philip Pardey
Journal of Economic History, March 2015, Pages 219-249
Abstract:
U.S corn output increased from 1.8 billion bushels in 1879 to 12.7 billion bushels in 2007. Concurrently, the footprint of production changed substantially. Failure to take proper account of movements means that productivity assessments likely misattribute sources of growth and climate change studies likely overestimate impacts. Our new spatial output indexes show that 16 to 21 percent of the increase in U.S. corn output over the 128 years beginning in 1879 was attributable to spatial movement in production. This long-run perspective provides historical precedent for how much agriculture might adjust to future changes in climate and technology.
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A bitter cup: Climate change profile of global production of Arabica and Robusta coffee
Christian Bunn et al.
Climatic Change, March 2015, Pages 89-101
Abstract:
Coffee has proven to be highly sensitive to climate change. Because coffee plantations have a lifespan of about thirty years, the likely effects of future climates are already a concern. Forward-looking research on adaptation is therefore in high demand across the entire supply chain. In this paper we seek to project current and future climate suitability for coffee production (Coffea arabica and Coffea canephora) on a global scale. We used machine learning algorithms to derive functions of climatic suitability from a database of geo-referenced production locations. Use of several parameter combinations enhances the robustness of our analysis. The resulting multi-model ensemble suggests that higher temperatures may reduce yields of C. arabica, while C. canephora could suffer from increasing variability of intra-seasonal temperatures. Climate change will reduce the global area suitable for coffee by about 50 % across emission scenarios. Impacts are highest at low latitudes and low altitudes. Impacts at higher altitudes and higher latitudes are still negative but less pronounced. The world’s dominant production regions in Brazil and Vietnam may experience substantial reductions in area available for coffee. Some regions in East Africa and Asia may become more suitable, but these are partially in forested areas, which could pose a challenge to mitigation efforts.
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Exceptional twentieth-century slowdown in Atlantic Ocean overturning circulation
Stefan Rahmstorf et al.
Nature Climate Change, forthcoming
Abstract:
Possible changes in Atlantic meridional overturning circulation (AMOC) provide a key source of uncertainty regarding future climate change. Maps of temperature trends over the twentieth century show a conspicuous region of cooling in the northern Atlantic. Here we present multiple lines of evidence suggesting that this cooling may be due to a reduction in the AMOC over the twentieth century and particularly after 1970. Since 1990 the AMOC seems to have partly recovered. This time evolution is consistently suggested by an AMOC index based on sea surface temperatures, by the hemispheric temperature difference, by coral-based proxies and by oceanic measurements. We discuss a possible contribution of the melting of the Greenland Ice Sheet to the slowdown. Using a multi-proxy temperature reconstruction for the AMOC index suggests that the AMOC weakness after 1975 is an unprecedented event in the past millennium (p > 0.99). Further melting of Greenland in the coming decades could contribute to further weakening of the AMOC.
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Eric Njuki & Boris Bravo-Ureta
American Journal of Agricultural Economics, forthcoming
Abstract:
Analyses of the costs of regulating greenhouse gas emissions from dairy production, which could be used to assess the effectiveness of alternative policy measures, is a missing link in the literature. This article addresses this gap by establishing the economic impact associated with a hypothetical greenhouse gas environmental regulatory regime across major dairy producing counties in the United States. In doing so, the article makes three important contributions to the literature. First, it develops a comprehensive pollution index based on Environmental Protection Agency methodologies, which contrasts with previous studies that rely on partial measures based only on surplus nitrogen stemming from the over-application of fertilizer. Second, the article uses a directional output distance function, an approach that has not been employed previously to evaluate polluting technologies in the U.S. dairy sector. Third, the article incorporates a four-way error approach that accounts for unobserved county heterogeneity, time-invariant persistent technical efficiency, time-varying transient technical efficiency, and a random error. The results indicate that regulating greenhouse gas emissions from dairy farming would induce a 5-percentage point increase in average technical efficiency. In addition, the economic costs of implementing this hypothetical regulatory framework exhibit significant spatial variation across counties in the United States.
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Long-term decline of the Amazon carbon sink
R.J.W. Brienen et al.
Nature, 19 March 2015, Pages 344–348
Abstract:
Atmospheric carbon dioxide records indicate that the land surface has acted as a strong global carbon sink over recent decades, with a substantial fraction of this sink probably located in the tropics, particularly in the Amazon. Nevertheless, it is unclear how the terrestrial carbon sink will evolve as climate and atmospheric composition continue to change. Here we analyse the historical evolution of the biomass dynamics of the Amazon rainforest over three decades using a distributed network of 321 plots. While this analysis confirms that Amazon forests have acted as a long-term net biomass sink, we find a long-term decreasing trend of carbon accumulation. Rates of net increase in above-ground biomass declined by one-third during the past decade compared to the 1990s. This is a consequence of growth rate increases levelling off recently, while biomass mortality persistently increased throughout, leading to a shortening of carbon residence times. Potential drivers for the mortality increase include greater climate variability, and feedbacks of faster growth on mortality, resulting in shortened tree longevity. The observed decline of the Amazon sink diverges markedly from the recent increase in terrestrial carbon uptake at the global scale, and is contrary to expectations based on models.
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Causal feedbacks in climate change
Egbert van Nes et al.
Nature Climate Change, forthcoming
Abstract:
The statistical association between temperature and greenhouse gases over glacial cycles is well documented, but causality behind this correlation remains difficult to extract directly from the data. A time lag of CO2 behind Antarctic temperature — originally thought to hint at a driving role for temperature — is absent at the last deglaciation, but recently confirmed at the last ice age inception and the end of the earlier termination II. We show that such variable time lags are typical for complex nonlinear systems such as the climate, prohibiting straightforward use of correlation lags to infer causation. However, an insight from dynamical systems theory now allows us to circumvent the classical challenges of unravelling causation from multivariate time series. We build on this insight to demonstrate directly from ice-core data that, over glacial–interglacial timescales, climate dynamics are largely driven by internal Earth system mechanisms, including a marked positive feedback effect from temperature variability on greenhouse-gas concentrations.
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Yufei He, Paolo D'Odorico & Stephan De Wekker
International Journal of Climatology, March 2015, Pages 475–480
Abstract:
Many regions of the world are affected by a major land cover change resulting from the encroachment of woody plants and the conversion of grasslands into shrublands. In the southwestern United States, such a change in vegetation cover has been found to increase the winter nighttime temperature, thereby contributing to a positive feedback between shrub encroachment and microclimate in areas encroached by cold-sensitive shrubs. Temperature measurements show that winter minimum temperatures are on average ∼2 K higher in shrubland than in adjacent grassland sites. It is unclear how the nighttime warming induced by shrub encroachment compares with regional climate trends. We address this question by analysing both the historical and future regional temperature trends in central New Mexico. The estimated regional increase in minimum winter temperature ranges from 1 to 4 K per century using observations and climate models. Thus, the warming resulting from shrub encroachment is equivalent to a change in regional climate over a time period of century scale, which suggests that shrub encroachment has an overall important effect on the regional climate.